1. Field of the Invention
This invention relates to variable area nozzle vanes. The term "vane" is used herein to refer generally to blades, shutters and other plane or curved substantially laminar members.
2. Summary of the Prior Art
Vanes of variable area nozzles have, in general, a metal body to which are secured devices enabling the adjusting actuation of the vane, and a base plate of steel which protects the metal body from the hot gases of the jet confined by the nozzle and ensures fluid-tightness with respect to adjacent vanes. The base plate supports longitudinally thereof a projection of triangular shape which enables the formation of an aerodynamic profile with the adjacent blades, and also serves cooling purposes.
The need to lighten such structures leads to the replacement at least partially of the components of the nozzle, generally of steel, by lighter materials, such as structures of the sandwich or alternatively honeycomb type. The problem then arises of providing a connection between the two materials having different coefficients of expansion and liable to be subjected to different temperatures. French Pat. No. 2,397,534 shows a joint or seal between the downstream ends of the divergent vanes, subject to the hot gas flow from the engine, and the downstream ends of the outer vanes which are subject to the external ambient temperature. The joint or seal comprises at least one elongate slot, of which the axis is approximately parallel to the genatrix of the divergent vane, in which the pivot is capable of being displaced longitudinally, the slot and the pivot each being fixed to a respective vane. No indication is given in this prior patent specification regarding securing together of the longitudinal edges of these vanes.
This previously proposed arrangement has, moreover, as its objective the facilitating of the relative displacement of a divergent vane with respect to an outer vane during changes in the configuration of the convergent-divergent blade assemmbly, the distance separating the upstream end of the convergent vanes and the downstream ends of the divergent vanes being variable in accordance with the profile which is required.
An object of the present invention is to provide a variable area nozzle vane of lightweight but capable of accommodating temperature differentials and providing for ready sealing and connection with adjacent vanes.